In a conventional type of color image converting apparatus, when inputting a color image signal and executing color processing to convert the color image signal to color image data for forming a color image, if color image data at a position exceeding a reproducible color space of the image forming device is inputted, 1 a method of detecting and outputting a position within the reproducible color space closest to the position of the color image data, or 2 a method of compressing the input color image toward the center of gravity of the reproducible color space and outputting it is employed.
However, in the conventional technology as described above, in the method 1, as a position within a reproducible color space closest to a color image data position is detected and outputted, a color exceeding the reproducible color space is converted to a color at an utmost periphery of the reproducible color space, and if there is a color at the utmost periphery of the reproducible color space, the converted color becomes the same as the color originally existing there, which is disadvantageous.
Especially, in case of a synthetic image formed on a computer screen, if a color which should originally be different is outputted as the same color, it is remarkable, and the outputted image gives an impression that the image is different from that of the computer screen.
In the method 2, an input color image signal is compressed toward the center of gravity of a reproducible color space, so that the problem in the method 2. does not occur, but if the input color image signal is substantially included in a reproducible color space, or when only a color having a specific hue exceeds a reproducible color space, even a color within the reproducible color space is converted in a direction toward non-color, and an image generally not having color attractiveness may be outputted.